Forces 3b

Something that will return to its original shape after being stretched.

8b) What happens to energy when work is done on an elastic object by a stretching force?

Elastic potential energy is stored in the object as the object is stretched, when released the energy changes to kinetic and a little heat.

9) How do you calculate extension from a length?

Extension=current length-original length.

10) Describe how a spring extends in terms of the forces acting upon it:

As the force on the spring increases, the extension increases, as it is directly proportional as long as it has not exceeded its limit of proportionality, according to Hooke's Law. On a graph, the line would be straight with a positive gradient.

11a) What is 'Spring constant'?

The amount of force per unit of extension to extend a spring.

11b) How do you calculate the extension using the Hookes law formula?

Force(N)=Spring constant(N/m)*extension(m)

12) Describe the force-extension graphs for a spring, a rubber band and a polythene bag:

Spring, straight positive gradient until limit of proportionality.

Rubber band is curved, the force doubles, the extension more than doubles.

Not directly proportional, stretches slowly to begin with, then very quickly (opposite to rubber band)